Adjustable tap



March 15, 1932. E. A. WALKER ifi w llfifi ADJUSTABLE 'TAP Filed July 27,1929' 30 bars.

Patented Mar. 15,1932

- (UNITE u jsrArss* WORCESTER, MASSACHUSETTS ADJUSTABLE 'i'lipApplication filed July 27,

This invention relates to taps particularly designed for cutting screwthreads in holes of relatively large diameter, the threads beingcommonly of relatively fine pitch.

* It is the general object of my invention to provide a tap for suchpurposes in which the cutting teeth are formed on separate'cutter bars,and in which provision is made for accurate radial adjustment of saidbars to compensate for wear or regrinding of the teeth.

A further object of the invention is to provide improved means forholding the cutter bars firmly seated in the supporting member or head.v

My invention further relates to arrangements and combinations of partswhich will be hereinafter described and more particularly pointed out inthe appended claims;

A preferred form ofthe invention is shown in the drawingsin which: V

Fig. 1 is a side elevation of my improved tap i Fig. 2 is an end viewthereof, partly broken away;

Fig. 3 is a side elevation of one of the cutter bars; and

Fig. 4 is a partial end elevation, showing the manner of radiallyadjusting the Referring to the drawings, my improved tap comprises asupporting member 10 adapted tobe mounted upon a driving shaft orspindle in any convenient or desired manner.

The member 10 is provided with a series of V brace and closely engagethe sides of the member 10. The projections 16 thus serve to effectivelyprevent axial or endwise movement of the cutter bars 14. I v VCylindrical projections or bosses 18-project from the side faces of themember 10 and cutter ts); sei'mim. 381327.

'provideshoulder's 19 on which thejproieetions '16 abut and aresupported,it being noted that the projections extend rearwardly, or in adirection away'from the teeth.

Segmental recesses 20' are formed in one? face of each bar 14 andprovideshoulders 22 '(Figs..2'and'3) adapted to be engaged by the enlargedheads 24 of binding screws 26, which a-re'threadedintothe member 10. Theouter face of each'bar 14 is provided wit-hteeth'T by which the desiredthread ma be cut.

nmvn'sr A. WALKER, or WORCESTER, MASSACHUSETTS, {ASSIGNORTOJOHN BIA'IH,or v Whehthe bars 14 are inserted in the slots 12 and theshoulders 22thereof are engaged V by the heads 24 of the'bi-nding screws 26, the

"projectionslti will be firmly seated. on the shoulders19and'at'the'same time the bars 14 will be held from :aXial movement by theprojections16.'

When the teeth onthe bars 14 become worn or arereground, the tap may berestored to i sizeby inserting shims '30'under each' of theten-thousalndthsofgan inch under size,- the I Eta-p can be restored tofull or standard size by inserting shims of three thousandths thick-method of adjusting thecutter bars is found so I ness under each of theprojections 16. This to:be' more accurate andr liable than theadzjustingwdievices heretofore used, suchfas ad-. 2 t

-je'cti'on's 16]:1180 very eifectively'preserve the justing screws orslidable wedges. The 'pro-' ='aXial alignment of the cutter bars during7 adjustment thereof.

i ':one or more shims 30' may be inserted under each I projection 16before the tap is --initia11y ground to size,in'whichcase the tap may beadjusted to cut undersize byremoving shims 30 of the desired thickness.It is not necessary to remove the bars 14 from the member 10 to insertor remove the shims 30,

-but merely looseningthe screws 26 is suffi- V cient.

"'HaVingfthuS described-myinventionrand Fthe advantages'thereof, I @do'not wish toibe :limited'tothe. details herein disclosed, otherwise thanas set forth in the claims, but what toothed edge and closely abuttingthe sides of said supporting member and thereby pre venting relativeaxial movement between said bar and said member, and means to hold saidbars seated in said slots.

2. An adjustable tap comprising a supporting member having a pluralityof axially extended slots spaced about its periphery, and a toothedcutter bar for each slot, each bar having an offset projection at eachend thereof extending in a direction opposed. to the toothed edge andclosely abutting the sides of said supporting member and therebypreventing relative axial movement between said bar and said member.

- 3. An adjustable tap comprising a supporting member having a pluralityof axially extended slots spaced about its periphery, and a toothedcutter bar for each slot, each bar having an oflset projection at eachend thereof extending in a direction opposed to the toothed edge andclosely abutting the sides of said supporting member and therebypreventing relative axial movement between .said bar and said member,said member being provided with shoulders underlying vand supportingsaid offset projections.

4. An adjustable tap as set forth in Claim 1, in which each of thecutter bars has shoulders on one side thereof and in which said holdingmeans comprises screws threaded in said supporting member and eachprovided with an enlarged head engaging one of said shoulders.

5. An adjustable tap comprising, a supporting member having an axiallyextending slot in its periphery, a cutter bar for said slot, said barhaving teeth projecting radially outwardly and also having an offsetprojection at each end thereof extending radially inward and closelyabutting the sides of said supporting member thereby to prevent relativeaxial movement between said bar and said member and means insertablebetween one of said projections and said member for adjusting therelative radial position of said bar in its slot.

6. An adjustable tap comprising a supporting member having an axiallyextending slot in its periphery, a cutter bar for said slot, said barhaving teeth projecting radibetween one of said projections and saidmember for adjusting the relative radial position of said bar in itsslot, said member being provided with a shoulder overlying andsupporting said projections.

In testimony whereof I have hereunto affixed my signature.

ERNEST A. WALKER.

ally outwardly and also having an ofl'set pro- I jection at each endthereof extending radially inward and closely abutting the sides of saidsupporting member thereby to pre vent relative axial movement betweensaid bar and said member, and means insertable

